Writing nib

ABSTRACT

Flexible nib for writing instrument includes core comprising flexible sheet having planar surface and opposite sawtooth surface formed by individual longitudinally extending triangular segments integrally connected together at their bases in side-byside fashion. Longitudinally extending notches are located in sides of triangular segments, and longitudinally extending flat portions are located at apex of each triangular segment on each side of each segment. Flexible sheet may be formed into cylinder with planar surface thereof on outside and longitudinally extending flat portions of adjacent triangular segments engaging one another. Notches cooperate with notches of adjacent triangular segments to form longitudinal passageways when flexible sheet is formed into cylinder.

Elrtited States Patent [1 1 N akano [451 Apr. 24, 1973 WRITING NIB [75] Inventor: Kan Nakano, Tondabayashi, Japan [73] Assignee: Tsukasa Felt Shoji Kabushiki Kaisha, Tokyo, Japan [22] Filed: Dec. 28, 1970 [21] App1.No.: 101,905

[52] US. Cl ..401/292, 401/199 [51] lint. Cl ..A46b 11/00, B43k 1/02 [58] Field of Search ..401/198, 199, 292

' [56] References Cited UNITED STATES PATENTS 3,424,539 H1969 Jenkins ..4()l/292 3,586,454 6/1971 Funahashi ..401/198 FOREIGN PATENTS OR APPLICATIONS I 1,903,452 8/1970 Germany ..401/292 Primary ExaminerLawrence Charles -Attorney-Connolly & Hutz [57] ABSTRACT Flexible nib for writing instrument includes core comprising flexible sheet having planar surface and opposite sawtooth surface formed by individual l0ngitudinally extending triangular segments integrally connected together at their bases in side-by-side fashion. Longitudinally extending notches are located in sides of triangular segments, and longitudinally extending flat portions are located at apex of each triangular segment on each side of each segment. Flexible sheet may be formed into cylinder with planar surface thereof on outside and longitudinally extending flat portions of adjacent triangular segments engaging one another. Notches cooperate with notches of adjacent triangular segments to form longitudinal passageways when flexible sheet is formed into cylinder.

- 4 Claims, 4 Drawing Figures WRITING NIB The present invention relates to a flexible nib for a writing instrument, and more particularly to a writing nib fabricated from durable thermoplastic material and characterized by its fine writing quality.

Many writing instruments used today include felt or fiber writing nibs formed by bonding the felt or fibers together with a synthetic resinous adhesive. Also, U. S. Pat. No. 3,328,216, granted Aug. 29, 1967, describes a writing instrument that includes a nib with a starshaped orifice therein. Felt and fiber writing nibs are easily worn away in use or deformed to such an extent that further use becomes impossible. On the other hand the particular writing nib disclosed in U. S. Pat. No. 3,328,216 is resistant to writing wear. However, being a drawn product the ink flow orifice of the writing nib is usually quite large and it is impossible to provide indentations to hold or otherwise retain the ink within the ink flow orifice. Accordingly, often the ink drips out of the exposed end of the writing instrument or flows back into the ink reservoir. In many instances, ink dripping or backflow may be prevented or. substantially eliminated by narrowing the ink flow orifice, butnarrowing sometimes causes insufficient ink flow for writing. In cases where more than one ink flow orifice is provided for the purpose of achieving adequate ink flow, the desirable elasticity of the writing nib is lost and the instrument becomes scratchy during the writing process thereby deteriorating the writing quality of the instrument. Thus, it is quite difficult to provide a flexible writing nib with an adequate ink flow orifice.

SUMMARY OF THE INVENTION The primary objective of the present invention is to provide a flexible nib for a writing instrument which avoids the disadvantages of the prior art devices.

Another object of the present invention is to provide a flexible writing nib which is easy to produce and assemble, and which functions in a highly efficient and beneficial manner during the writing process.

In accordance with the present invention a flexible nib for a writing instrument includes a core that comprises a flexible sheet having a planar surface and an opposite sawtooth surface formed by individual longitudinally extending triangular segments integrally connected together at their bases in side-by-side fashion. Longitudinally extending notches are located in the sides of the triangular segments. Also, longitudinally extending flat portions are located at the apex of each triangular segment on each side of each segment so that the flexible sheet may be formed into a cylinder with the planar surface thereof on the outside. When the flexible sheet is formed into the cylinder the longitudinally extending flat portions of adjacent triangular segments engage one another, and the notches form longitudinal passageways through the cylinder.

Preferably, the core of the flexible writing nib is fabricated from thermoplastic material such as polyamide or polyacetal resin. The sawtooth surface is preferably formed by six longitudinally extending triangular segments with each segment having a similar cross sectional configuration in the form of an equilateral triangle.

The flexible writing nib of the present invention also includes a cylindrical sheath that surrounds the core for maintaining the core in its cylindrical configuration. Preferably, the interior surface of the cylindrical sheath includes a plurality of spaced apart inwardly directed longitudinal projections that engage the exterior surface of the cylinder and define a plurality of longitudinally oriented the sheath.

BRIEF DESCRIPTION OF THE DRAWING being in its planar position just prior to being formed into a cylinder; and

FIG. 4 is a side elevational view of a writing instrument including a flexible nib according to the present invention with parts of the writing instrument broken away to show detail.

DETAILED DESCRIPTION OF THE INVENTION The flexible writing nib 7 of the present invention comprises a core member 4 and a cylindrical sheath 6 that surrounds the core .member. As shown best in FIGS. 2 and 3, the core member comprises a plate piece or flexible sheet 1 having a planar surface 2 on one side thereof and a sawtooth surface 3 on the opposite side thereof. The sawtooth surface is formed by individual longitudinally extending triangular segments 3 integrally connected at their bases in side-by-side fashion. Longitudinally extending V-grooves or notches 3b are located in the sides of the triangular segment near the base of each of the segments. Additionally, longitudinally extending flat portions 3a are located at the apex of each triangular segment 3 on each side of each segment. In the embodiment of the present invention illustrated in FIGS. 2 and 3 the plate piece or flexible sheet 1 has six longitudinally extending triangular segments 3, and each segment has a similar cross sectional configuration in the form of an equilateral triangle. Thus, the apex of each longitudinally extending triangular segment is inclined at The plate piece or flexible sheet 1 is assembled to form the core member 4 by simply rolling the flexible sheet into a cylindrical configuration with the planar surface 2 of the sheet 1 on the outside of the cylinder. As shown best in FIG. 2, when the flexible sheet is formed into a cylinder to thereby form the core 4 of the writing instrument, adjacent sides of the longitudinally extending triangular segments 3 engage one another so that the flat portions 3a meet one another and the notches or V-grooves 311 form longitudinal passageways through the cylinder. Axial ink ducts of strong capillary action are also formed by a meeting of the flat portions of the individual longitudinally extending triangular segments 3. Axial ink ducts 8 of relatively wide open passageways between the cylinder and The writing nib of the present invention is assembled.

by inserting the core member 4 into the cylindrical sheath 6. The sheath includes a plurality of spaced apart inwardly directed longitudinal projections 5 on the interior surface thereof which projections engage the exterior of the core 4. Preferably, the projections 5 may be discontinuous or irregular in length. After the core 4 and cylindrical sheath 6 are fitted together, as shown best in FIG. 2, the end portions thereof are tapered, as best shown in FIG.. 1, to thereby expose the core. As shown in FIG. 2, the radial orientation of the grooves, except for 8' terminate midway on the inclined writing tip end of the core. In other words, the

extreme tip of the writing nib is free of any interruption except for the juncture adjacent the groove 8. This feature prevents scratchness during the writing operation, and also provides excellent quality writing. The cylindrical sheath 6 which surrounds the core 4 forms an axial gap or space between the projections 5 and the outside surface of the core 4. Ink flows between these passageways because the projections 5 are either sharply pointed or discontinuous.

As shown best in FIG. 4, the flexible writing nib 7 has its writing end located exteriorly of the pen body 10. The other end of the writing nib is positioned in an ink reservoir 11 located inside the pen body 10. The writing nib 7 is secured to the pen body 10 by means of a nib holder 12, as shown best in FIG. 4.

Ink from the reservoir 11 flows through the writing nib 7 in the following manner. Ink is supplied to the exterior tip of the nib through both the core passageways 8 and the passageways formed between the exterior of the core'and theinside surface of the cylindrical sheath 6. The ink in the spaces between the exterior of the core and inside surface of the cylindrical sheath is delivered to the center of the core via the groove 8. Thus, the ink supply is extremely sufficient for writing and high quality writing is accomplished in an effortless manner. Ink dripping and backflow are prevented due to the relatively small dimensions of the ink flow passageways.

Preferably, the core 4 and the cylindrical sheath 6 that surrounds the core to form the writing nib 7 are fabricated from thermoplastic material such as high wear proof polyamide resin or polyacetal resin. Such construction provides a fine writing instrument for use with-quick drying inks or water ink.

Lastly, in one of the desired embodiments of this invention, the pitch of the projections 5 of the cylindrical sheath 6 is from 0.10 mm to 0.25 mm and the height of the projections is from 0.05 mm to 0.1 mm; and the groove 8 in the core member '4 shows the valve from 0.08 mm to 0.12 mm at the most expanded portion and from 0.01 mm to 0.05 mm at the most narrowed portion. The pitch 3b of the notches of the groove 8 is from 0.08 mm to 0.15 mm.

What is claimed is:

l. A flexible nib for a writing instrument including a core comprising a flexible sheet having a dplanar surface and an opposite sawtooth surface forme by individual longitudinally extending triangular segments integrally connected together at their bases in side-by-side fashion, and longitudinally extending notches in both sides of each of the triangular segments whereby the flexible sheath may be formed into a cylinder with the planar surface thereof on the outside and the notches forming longitudinal passageways through the cylinder, and a cylindrical sheath surrounding the core for maintaining it in its cylindrical configuration, the interior surface of the cylindrical sheath having a plurality of spaced apartinwardly directed longitudinal projections that engage the exterior surface of the cylinder and define a plurality of longitudinally oriented passageways between the cylinder and the sheath.

2. A flexible nib for a writing instrument as in claim 1 

1. A flexible nib for a writing instrument including a core comprising a flexible sheet having a planar surface and an opposite sawtooth surface formed by individual longitudinally extending triangular segments integrally connected together at their bases in side-by-side fashion, and longitudinally extending notches in both sides of each of the triangular segments whereby the flexible sheath may be formed into a cylinder with the planar surface thereof on the outside and the notches forming longitudinal passageways through the cylinder, and a cylindrical sheath surrounding the core for maintaining it in its cylindrical configuration, the interior surface of the cylindrical sheath having a plurality of spaced apart inwardly directed longitudinal projections that engage the exterior surface of the cylinder and define a plurality of longitudinally oriented passageways between the cylinder and the sheath.
 2. A flexible nib for a writing instrument as in claim 1 wherein the core is made of thermoplastic material.
 3. A flexible nib for a writing instrument as in claim 2 wherein the thermoplastic material is polyamide resin.
 4. A flexible nib for a writing instrument as in claim 2 wherein the thermoplastic material is polyacetal resin. 